refactor: update site URL to be single source of truth (#143)

* wip: astro config to use .ts instead of .mjs

* fix: remove invalid prop in astro config

* refactor: single source of truth for site url

* refactor: make minor updates due to astro.config.ts

---------

Co-authored-by: satnaing <satnaingdev@gmail.com>

src/content/blog/how-to-add-an-estimated-reading-time.md

@@ -37,7 +37,7 @@ export function remarkReadingTime() {
 }
 ```
 
-Step (3) Add the plugin to `astro.config.mjs`
+Step (3) Add the plugin to `astro.config.ts`
 
 ```js
 import { remarkReadingTime } from "./src/utils/remark-reading-time.mjs"; // make sure your relative path is correct

src/content/blog/how-to-configure-astropaper-theme.md

@@ -34,17 +34,6 @@ export const SITE = {
 };
 ```
 
-Then, replace site property of `astro.config.mjs` file with your own deployed domain. _(You can also omit this step if you don't have deployed domain yet or you are still in development mode)_
-
-```js
-// file: astro.config.mjs
-export default defineConfig({
-  site: "https://astro-paper.pages.dev/", // replace this with your deployed domain
-  integrations: [...],
-  ...
-)}
-```
-
 Here are SITE configuration options
 
 | Options            | Description                                                                                                                                                  |